1. Field of the Invention
The present invention relates to a test apparatus.
2. Description of the Related Art
In recent years, various kinds of semiconductor devices are known which are employed in various kinds of electronic devices. Examples of such semiconductor devices include: (i) memory devices such as DRAM (Dynamic Random Access Memory), flash memory, and the like; (ii) processors such as a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a micro-controller, and the like; and (iii) multifunctional devices such as a digital/analog mixed device, SoC (System On Chip), and the like. In order to test such semiconductor devices, a semiconductor test apparatus (which will also be referred to simply as “test apparatus”) is employed.
The test items for such semiconductor devices can be broadly classified into (i) functional verification tests (which will also be referred to simply as the “functional tests”) and (ii) DC (Direct Current) tests. With a functional verification test, judgment is made whether or not a DUT (device under test) operates normally according to its design. Examples of such a functional verification test include identification of defect positions, and acquisition of evaluation values which indicate the performance of the DUT. Examples of such a DC test include DUT leak current measurement, operation current (power supply current) measurement, breakdown voltage measurement, and the like.
The functional verification test and the DC test have various kinds of specific content for each of the various kinds of semiconductor devices. For example, in the memory functional verification test, first, a predetermined test pattern is written to the memory. Subsequently, the data thus written to the DUT is read out from the memory, and the data thus read out is compared with an expected value so as to generate pass/fail data which represents the comparison result. Although RAM and flash memory are both memory devices, different test patterns are written to the RAM and the flash memory. Furthermore, there is a difference in the writing/readout data units and the writing/readout sequence between the RAM test and the flash memory test.
In a D/A converter functional verification test, a digital signal is supplied to the input terminal of the D/A converter while sweeping the digital signal value in a predetermined range. With such an arrangement, an analog voltage is output from the D/A converter according to the respective digital values, and the analog voltage values thus output are measured. As a result, the offset voltage or the gain is measured.
On the other hand, in an A/D converter functional verification test, an analog voltage is supplied to the input terminal of the A/D converter while sweeping the analog voltage in a predetermined range. With such an arrangement, digital values are output from the A/D converter according to the respective analog voltage values, and the digital values thus output are measured. As a result, the INL (Integral Nonlinearity) or DNL (Differential Nonlinearity) is measured.
Micro-controllers, digital/analog mixed devices, SoC, and the like, each include various kinds of built-in components such as RAM, flash memory, a D/A converter, and an A/D converter. Thus, there is a need to perform respective functional verification tests for the built-in components.
Furthermore, in many cases, a boundary scan test is executed for such a semiconductor device.
In the present specification, the test item, test pattern format, test sequence, test condition, and the like, are included in the concept that will be referred to as the “test algorithm”.
With conventional techniques, there are commercially available test apparatuses each designed as a dedicated test apparatus or an optimized test apparatus for each kind of such a semiconductor device, or for each test item. Thus, the user, i.e., the designer or the manufacturer of such a semiconductor device must purchase a test apparatus configured to support a particular kind of DUT and particular test items. Furthermore, in order to execute a test item which is not supported as a standard test item by a given test apparatus, the user must purchase an additional hardware component required for the test item, and must install the additional hardware component on the test apparatus.
In addition, the test apparatus cannot operate on its own. That is to say, there is a need to install a test program on the test apparatus so as to control the test apparatus. With conventional techniques, in order to execute the user's desired test, the user must develop a test program for controlling the test apparatus using a software development support tool, which is a burden on the user.
In particular, in many cases, the format is modified when the generation changes. In some cases, the test algorithm must be changed every time the standard is changed. In other words, the user must personally modify an enormous amount of test programming every time the standard is changed.
Furthermore, conventional test apparatuses are designed mainly for the purpose of testing during mass production. Thus, such conventional test apparatuses have a problem of a large size and a problem of an extremely high cost. This prevents such a test apparatus from effectively being applied to the design phase and the development phase before the mass production phase. Conventionally, in order to test a semiconductor device in the development phase, the user must separately prepare a power supply apparatus, an arbitrary waveform generator, an oscilloscope, a digitizer, and the like, and must combine these components so as to construct a test system of the user's own before the user measures the desired characteristics. For example, let us consider a case in which the user desires to test only a leak current of a processor. Conventional processor test apparatuses each have a function for measuring the leak current. However, it is unrealistic to purchase and employ such a large-size and high-cost test apparatus only for the leak current measurement. Thus, conventionally, the user must construct a measurement system using a power supply apparatus configured to generate a power supply voltage for a processor, an ammeter configured to measure a leak current, and a controller configured to control the processor to be set to a desired state (vector).
On the other hand, in a case in which the user desires to evaluate an A/D converter, the user must construct a measurement system using a power supply configured to generate a power supply voltage for the A/D converter, and an arbitrary waveform generator configured to control the input voltage to be input to the A/D converter.
Such a test system thus constructed for particular purposes has a problem of poor versatility. Furthermore, such a test system leads to a problem of complicated control operations and a problem of complicated data processing.
It should be noted that the problems described above have been uniquely studied by the present inventors, and are by no means within the scope of common and general knowledge of those skilled in this art.